Add get_or_insert_with_key

[pikatos]

Add get_or_insert_with_key variant. If the key is needed to create a new value to populate the cache, using only get_or_insert implies the use of a cloneable key to be able to capture the key in the provided closure. Wrapping the key with Rc and using get_or_insert_ref just for that seems overkill.

let key = Rc::new("mydomain.com".to_owned());
cache.get_or_insert_ref(&key, domain_cert_generator(key.clone()));

becomes:

cache.get_or_insert_with_key("mydomain.com".to_owned(), generate_domain_cert);

[Copilot]

Pull request overview

This PR extends the LruCache API with *_or_insert_with_key variants that pass &K into the value-construction closure, reducing the need for cloning keys solely to capture them in FnOnce.

Changes:

• Added get_or_insert_with_key, try_get_or_insert_with_key, get_or_insert_mut_with_key, and try_get_or_insert_mut_with_key.
• Refactored existing get_or_insert* / try_get_or_insert* methods to delegate to the new *_with_key variants.
• Added unit tests covering the new APIs.

---

💡 Add Copilot custom instructions for smarter, more guided reviews. Learn how to get started.

[jeromefroe]

Thank you for the contribution @pikatos